Hemostatic patch

ABSTRACT

A fibrogen-free substrate having as a hemostatic agent on a surface thereof a mixture of a clot-promoting amount of thrombin and an amount of epsilon aminocaproic acid (EACA) effective to accelerate the rate of blood clotting induced by the thrombin is useful as a hemostatic patch which is safe, inexpensive and which rapidly controls bleeding from a wound. A patch which rapidly stanches the flow of blood from a lesion on a parenchymal organ by pressing it against the surface of the organ for 3-5 minutes, is produced by applying thrombin, EACA and CaCl 2  to a rigid sheet of biodegradable foam, such as an absorbable gelatin sponge, and compressing the dry sheet to produce a flexible sheet which conforms to the contour of the organ without the necessity of pre-moistening. The EACA raises the pH of the acidic fluid associated with the wound and thereby accelerates the activation of the thrombin.

This application is a continuation of application Ser. No. 08/146,360,filed Nov. 3, 1993, now abandoned.

BACKGROUND OF THE INVENTION

A hemorrhage of a blood vessel, body tissue, organ or bone can result inblood loss leading to hypovolemic shock and death. In hemophiliacs andpatients receiving anticoagulant medication, such as often prescribedpost-operatively for heart surgery, the problem of rapid blood loss iseven more acute.

Attempts have been made to devise a fast, effective and inexpensivemethod for curbing blood loss, including pastes containingcoagulation-enhancing factors. One such coagulation enhancing substanceemployed to assist a cessation of bleeding or "hemostasis" is humanfibrinogen, most commonly employed as a "fibrin glue".

Fibrin glue is composed of a mixture of human fibrinogen and bovinethrombin. It is sold as a kit containing separate vials of fibrinogenand thrombin solutions. These solutions are mixed together and appliedto the wound in various ways, including as a paste, as a spray or on apatch.

Fibrin glue, however, is an inconsistent and ineffective therapy forhemostasis. The mixing, soaking, and coating of a patch with fibrin gluerequires time-consuming and cumbersome procedures. Each of thepreparation steps introduces potential errors and thus their efficacyvaries with the experience of operating room personnel. Moreover, duringthe preparation of such solution, further hemorrhage occurs and thesolutions are washed away by intense bleeding. Despite the headway madein fibrinogen compositions and surgical techniques, these pitfalls inachieving hemostasis underscore the need for development of a suitableproduct.

An improvement over fibrin glue, marketed in Europe consists of abiodegradable collagen patch onto which is impregnated bovine thrombin,aprotinin and human fibrinogen (the "TAF" patch). An example of a TAFpatch is the TachoComb® patch marketed in Europe by Hafslund NycomedPharma, DE. The patch also contains calcium chloride to enhancecoagulation. In use, this patch is removed from its package, dipped intosaline solution and applied to the bleeding organ with light pressurefor at least five minutes. When the bleeding has stopped, the patch isleft in place by the surgeon and the cavity closed.

A major drawback to the use of fibrin glue and the TAF patch is thatboth contain human fibrinogen, a protein purified from human blood.Because of the high risk of HIV and hepatitis viral contamination, theFood and Drug Administration revoked the use of human fibrinogen in theUnited States in 1978. In addition to the safety concerns, humanfibrinogen purified from human plasma is very expensive.

A TAF patch also requires refrigeration in order to stabilize thecoagulation-enhancing agents contained in the patch. This requirementprohibits certain field applications of the patch, where refrigerationfacilities are unavailable. Another problem with a TAF patch thatsurgeons cite is its inflexibility, that is, the patch does not conformeasily to the shape of the body surface to which it is applied.

A hemorrhage of a parenchymal organ, such as the spleen, liver, lung orpancreas, which can result from trauma or surgery, is particularlydifficult to treat. Parenchymal organs are difficult to ligate becausethe tissue is easily torn, pulverized or crumbled. As a result, surgeonsoften resort to the use of electrocautery, which can lead to furtherdestruction of the patient's tissues.

Thus, an effective hemostatic patch is desired which is safe from deadlyviral contamination and even stops bleeding in the problematichemorrhages of parenchymal organs. A patch is further desired that isinexpensive, easy to use and that molds easily to body contours. Also aneed exists for a patch that withstands elevated temperatures withoutrequiring refrigeration and retains hemostatic efficacy.

SUMMARY OF THE INVENTION

According to the present invention, an effective hemostatic patch isproduced comprising a matrix and at least one hemostatic agent, epsilonaminocaproic acid. The patch does not require as an ingredient anyexogenous human protein, such as fibrinogen, which thereby avoidsintroduction of unsafe contaminating viruses. The present hemostaticpatch is inexpensive, easy to use, thermally stable, and antibacterial,as well.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 displays a control experiment showing the thrombin activation at37° C. and physiological pH.

FIG. 2 demonstrates the effects of pH on thrombin activation at 37° C.

FIG. 3A and FIG. 3B each show inhibition by EACA of Staph. aureus growthin the presence of various concentrations of EACA.

FIGS. 4A and FIG. 4B each show inhibition by EACA of E. coli growth inthe presence of various concentrations of EACA.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

According to the present invention, a hemostatic patch is provided thatcomprises a shaped structural element that is a biodegradable matrix,such as absorbable gelatin sponge or calcium alginate, to which isapplied a hemostatic agent that contains epsilon aminocaproic acid,"EACA." EACA is an inhibitor of clot degradation. In the body, clotformation and clot breakdown are competing processes. EACA inhibits theproduction of plasmin, an enzyme that degrades clots. Plasmin degradesclots by solubilizing fibrin, an important component of clots, in aprocess called fibrinolysis. By inhibiting the formation of plasminwhich breaks down clots, EACA inhibits fibrinolysis and drives thereaction conditions at the patch/biological interface in favor of clotformation. A hemostatic patch according to the invention thus comprisesan amount of EACA effective for inhibiting fibrinolysis.

Surprisingly, it has been discovered that EACA functions as a hemostaticagent in a patch in a manner that approximates the effectiveness offibrinogen, a coagulation factor that, in solution, converts to fibrinin the presence of thrombin. Fibrinogen is an active ingredient found inother hemostatic patches. EACA, however, is devoid of the hazards thataccompany use of fibrinogen.

Moreover, according to the present invention, it has been determined,surprisingly that EACA in the matrix of a patch provides an alkalineenvironment that accelerates the activation of thrombin. In comparisonwith thrombin activation measured in the absence of EACA (FIG. 1, closedboxes), EACA greatly increases thrombin's activity FIG. 2). Thisphenomenon holds true whether the EACA acts on thrombin present in theblood endogenously or on thrombin that is supplied externally in apatch. Thus, it has been discovered that a patch comprising EACA exertsa dual hemostatic action by (1) slowing clot degradation by inhibitingplasmin formation and (2) accelerating clot formation by activatingthrombin.

Therefore, a method is provided for accelerating the activity ofthrombin by increasing the pH of the local environment of a patchaccording to the invention. Such a patch comprises a matrix and a"thrombin enhancing compound" capable of raising the pH in a solution inthe local environment of the patch sufficient to increase the activationof thrombin. Such a compound is capable of raising the pH of the localenvironment to a pH in the range of 7.0-9.0 inclusive, moreadvantageously between pH 7.02-8.02 inclusively, and even furtheradvantageously, between pH 7.62-8.02, inclusively.

According to the present invention, an alkaline solution is created inthe local environment of the patch as the thrombin enhancing compoundsolubilizes upon its contact with blood. Then, thrombin present in theblood and, optionally, thrombin provided as an exogenous ingredient ofthe patch mixes with the alkaline solution in the local environment of apatch and thereby is activated.

Advantageously, the thrombin-enhancing compound provided in the patchfor increasing pH is EACA. A "sterile buffer" which is pharmaceuticallyacceptable and capable of buffering the local pH in the patch toalkaline conditions, (i.e., between a pH of 7.0-9.0, more advantageouslypH 7.02-8.02, and even further advantageously, 7.62-8.02), is suitableas a thrombin-enhancing compound, as well. For example, Tris buffer isan effective thrombin-enhancing sterile buffer, as shown in FIG. 2, opendiamond-shaped graphical plot. Other sterile buffers that buffer the pHin this range are contemplated, such as Hepes buffer, for example.Accordingly, in a more advantageous patch, EACA and Tris (or other)buffer both are provided in the matrix of the patch.

Yet another surprising advantage of EACA has been discovered. EACApossesses antibacterial properties. According to the present invention,it has been demonstrated that EACA exerts dose-dependent inhibition ofboth S. aureus and E. coli growth (FIGS. 3A, 3B and 4A, 4B,respectively). Therefore, the EACA/matrix patch according to the presentinvention is very desirable for its antibacterial effects onmicroorganisms present at the wound site where a patch is applied.

Another advantage of EACA is that it contains no foreign peptides ofanimal origin. For example, a non-human fibrinogen hemostatic agent insome humans will trigger an immune response or allergic-like reaction.

Thus, a patch according to the invention can contain as a solehemostatic agent EACA dispersed within a matrix or applied to a surfaceof a matrix in an amount effective for inhibiting fibrinolysis andthereby stimulating clot formation. A biodegradable "matrix" as referredto herein, and as employed in any of the present embodiments of theinvention, is selected from, but not limited to, the group consisting ofabsorbable gelatin sponge, calcium alginate, calcium/sodium alginate,collagen, and oxidized regenerated cellulose. A matrix of other forms ofcollagen, such as crosslinked collagen, esterified collagen orchemically modified collagen as taught by U.S. Pat. No. 4,390,519 toSawyer, and other conventional matrices utilized in hemostatic patches,are contemplated for use with EACA according to the present invention.Four matrices that are advantageous for use with EACA include absorbablegelatin sponge, calcium alginate, calcium/sodium alginate, and collagen.

A first embodiment of the invention therefore provides a patchcomprising a matrix of absorbable gelatin sponge "G" and a hemostaticagent, EACA "E." This embodiment, "GE", preferably also can containcalcium, "G(Ca++)E." Advantageously, the GE or G(Ca++)E patch need notcontain or fibrinogen to function effectively to control hemorrhage of aparenahymal organ. As a result, both GE and G(Ca++)E, have good thermalstability and can be stored for months to a few years withoutrefrigeration and losing effectiveness. The GE and G(Ca++)E patches areuseful for field and emergency use, since each may be stored in aready-to-use state for a lengthy period, even in absence ofrefrigeration. Both also are much less expensive to make than patcheswhich contain fibrinogen.

The many representative embodiments of the present invention arereferred to herein most easily by acronyms, e.g., GE. These acronyms areindicative of the individual components (Table 1) found in the patchescreated in accordance with the invention.

                  TABLE 1                                                         ______________________________________                                        PATCH COMPONENT CODES:                                                        ______________________________________                                        G          = gelatin foam patch alone, e.g., Gelfoam ®                    CA         = calcium alginate                                                 CVA        = calcium/sodium alginate, e.g., Kaltostat ®                   C or CVC   = collagen or collagen (Helistat ®), respectively              E          = EACA                                                             (Ca++)     = calcium                                                          T          = thrombin                                                         R          = RGD peptide                                                      P          = protamine sulfate                                                F          = Fibrinogen                                                       (f)        = freshly applied compound (Example 7)                             GT (Ca++) E                                                                              = "Hemarrest ™" patch                                           ______________________________________                                    

In other embodiments, a GE or G(Ca++)E patch further comprises aneffective amount of thrombin for stimulating hemostasis and thus isdesignated as "GTE" or "GT(Ca++)E." A thrombin molecule is most stableat temperatures between 2°-8° C. However, these patches can be storedfor a limited period of time at room temperature. In fact, becauseaddition of thrombin enhances the GE and G(Ca++)E patches'effectiveness, these patches are very useful outside the clinic forfield use, such as for emergency or military purposes.

Although it is understood that exposure to extreme environmentalconditions may render thrombin present in the patch partially or totallyinactive, the activity of the remaining GE or G(Ca++)E patch would notbe substantially affected.

In the GE and GE(Ca++) patches, and all patches described herein thatemploy an absorbable gelatin sponge^(USP) as a matrix, the matrix isadvantageously a flat layer of gelatin foam, more advantageously,Gelfoam®, and even more advantageously, compressed gelatin foam orcompressed GelFoam®. The effectiveness of patches of the presentinvention in promoting clot formation is enhanced by the latticestructure of the gelatin foam, which promotes enzyme substrateinteractions. In particular, the gelatin foam structure enhances contactbetween thrombin provided exogenously in the patch with endogenousfibrinogen present in the blood exuding from the wound.

Additional hemostatic agents can be applied to the GE patch in amountseffective for stimulating hemostasis, including, but not limited to:thrombin "T", an enzyme which converts fibrinogen to fibrin; calcium,sodium, magnesium or other ions that stimulate hemostasis; andoptionally, fibrinogen, "F".

In terms of ion additives, calcium chloride is generally a preferredadditive for introducing a calcium ion into the patch.

"EACA analogs," or compounds that possess a similar hemostatic activityand a chemical structure to that of EACA, can be used instead of, or inaddition to, EACA in a patch according to the invention. Possible EACAanalogs contemplated for addition to a matrix include EACA derivativeshaving bioisosteric functional groups. EACA's carboxylic acid group canbe substituted, for example, by sulfonic or sulfinic acid (--SO₂ H and--SO₃ H) or phosphonic acid groups. Examples of analogs include, but arenot limited, to 5-aminopentanoic a acid, 7-aminoheptanoic acid,8-aminooctanoic acid, provided that these compounds exert a hemostaticactivity.

The molecules "thrombin" and "fibrinogen" as defined herein are meant toinclude natural thrombin and fibrinogen molecules derived from an animalor human origin, a synthetic form or a recombinant form of themolecules, including functionally active analogs that effectivelymaintain the enzyme's clot promoting activity in an animal or human. Thespecies of animal from which the molecule is derived can vary anddepends on the intended use of the patch. For example, a patch intendedfor human use for safety reasons contains non-human thrombin, andpreferred in this context is bovine thrombin. By avoiding use of humanfibrinogen, risks associated with viral contamination of purified bloodproducts (particularly with fibrinogen) are minimized. Indeed, theingredients EACA, thrombin and GelFoam® all are approved by the U.S.Food and Drug Administration for human use.

In yet another embodiment, a patch is provided having a matrix composedof calcium-sodium alginate "CVA" or calcium alginate "CA," and ahemostatic layer of EACA "E." It is understood that calcium alginate canbe substituted for calcium/sodium alginate in the discussion andexamples hereafter, without substantial differences in results.

The embodiment, "CVAE", advantageously contains calcium ion and thrombinas well. It also is less expensive as compared with a patch thatcontains fibrinogen. Similar to the GE patch, the CAE patch can includeadditional hemostatic agents including, but not limited to, thrombin,calcium or sodium or other ions in amounts that are effective tostimulate or accelerate hemostasis. These patches further can containadditives as described herein, as well.

In another embodiment, an effective amount of the active peptide, RGD,"R" or RGDS effective to stimulate wound healing is added to a patchcomprising GE or CAE, and thus such a patch is designated as GER orCAER. The tripeptide RGD is composed of arginine, glycine and asparticacid, and optionally serine "RGDS," and is the active site of fibrinogenand fibronectin. RGD accelerates wound healing and is believed tostimulate fibroblast migration.

The RGD additive is also much less expensive than fibrinogen. RGD can besynthesized easily using conventional solid phase chemistry at afraction of the cost of obtaining fibrinogen, which currently must beobtained by purification from a natural source.

In yet another embodiment, an amount of the agent protamine sulfate "P"effective to neutralize heparin present in the local environment of thepatch is added to any of the aforementioned patches comprising EACA anda matrix. Protamine sulfate neutralizes heparin or vitamin K antagoniststhat are present in the blood of certain patients or animals beingtreated with a hemostatic patch. A patch comprising GEP or CAEP, forexample, is prescribed for persons undergoing parenteral therapy withheparin. In particular, a patch that further contains thrombin would beeffective in patients taking dicumarol. A patch containing protaminesulfate is preferably stored at refrigerated temperatures of 2-8 degreesCelsius to maintain the activity of protamine sulfate.

An additional advantage of the patches according to the presentinvention is that the matrices, such as absorbable gelatin sponge orcalcium alginate, and the hemostatic agents, especially EACA andthrombin, and the additive, RGD, all are relatively inexpensive. It isestimated that production of a "standard-size" rectangular patch ofabout 9.5×4.8 cm, having a thickness of about 2.5 mm would costsubstantially less than a TAF patch of the same size.

Patches according to the present invention exhibited efficacy ininducing hemostasis in freely bleeding lesions of the spleen, liver andkidney of an anesthetized pig. Surgical lesions induced in parenchymalorgans of pigs provide a good model system for hemostasis in theanalogous human organs as evidenced by preclinical studies performed onpigs and dogs for the TachoComb® patch. Schiele et al., ClinicalMaterials 9: 169 at page 172 (1992). See also, SWINE AS MODELS INBIOMEDICAL RESEARCH, Swindle, M., Iowa State Univ. Press (1992). Indeed,surprisingly, patches according to the present invention performedbetter than TachoComb® in the liver, while in the kidneys, the patchcontaining a matrix of GelFoam®, thrombin and 100 mg/cm² EACA performedequally as well as the TachoComb® patch. The results of that comparativeexperiment are presented in Example 3 herein.

Another important advantage of the present invention is its flexibility,that is, a patch is provided that easily conforms to the contours of anorgan or biological surface, making the manipulation of applying thepatch quicker to perform. As a result, there is less overall blood lossto the patient and less time is spent in surgery.

A hemostatic patch according to the present invention in employed byapplying a "wound-contacting" surface of the patch, a surface intendedto contact the wound and containing hemostatic agent(s) and optionallyadditives, to a bleeding wound. Then, the patch is maintained in contactwith the wound for a period of time sufficient for clotting to occur atthe interface between the hemostatic patch and the wound and forbleeding to be substantially arrested. Preferably the patch ismaintained in contact with the wound surface for a period of about 3-20minutes, advantageously 3-10 minutes, and more advantageously, 3-5minutes. Where EACA, thrombin, and calcium chloride all are presenton/in the matrix, the time period is preferably about 5 minutes. Thepatch is held in place against the biological surface preferably withlight pressure, preferably by means of a sterile saline soaked sponge.Alternatively, the patch may be held in place simply by applyingpressure to the patch by means of a gauze or other dry sterile material.Depending on the location of the wound, a bandage, including anelasticized bandage, can be wrapped around the patch so as to providelight pressure on the wound site.

In addition to inducing hemostasis, a patch according to the presentinvention is useful for hermetically sealing body tissue. For example,when air leaks from a wound in the lungs, a patch is applied to thesurface surrounding the wound, held in place with light pressure for aperiod of time adequate to induce hemostasis, as discussed above. Duringthat time, in addition to hemostasis, a hermetic seal forms.

Prior to applying the patch, it is preferable to soak the patch insterile saline solution. Such a step is not required, however. Use of ahemostatic patch according to the invention, without first soaking insaline solution permits quick and simple application of the patch infield situations, such as may be encountered by an emergency medicaltechnician or a military health-care worker.

In one embodiment, the patch is contained within a sealed sterilepackage which facilitates removal of the patch without contamination.Such a package for example, can be an aluminum foil pouch or otherconventional material that is easily sterilized. Radiation,advantageously gamma radiation, is applied to sterilize the patch andpackaging material together.

In another embodiment, a container having dual compartments is provided.A first compartment contains distilled water, sterile saline or asterile buffer, while the second compartment contains a patch accordingto the invention. In field use, the patch of the second compartment canbe readily dipped into an opened first compartment and subsequentlyapplied to the wound.

A preferred use of a patch according to the present invention is toinhibit or completely stop bleeding of a parenchymal organ, such as theliver, kidney, spleen, pancreas or lungs. Additional uses for such apatch include curbing bleeding of tissues during types of surgery suchas, but not limited to, internal/abdominal, vascular (particularly foranastomosis), ufological, gynecological (particularly for anepisiotomy), thyroidal, neurological, ENT, tissue transplant uses, anddental surgeries.

Another use of a hemostatic patch includes topical treatment, such asfor burn or tissue transplants. A patch intended for topical useaccording to the invention preferably contains additives, such asanti-infection medicaments. Bactericides, fungicides and wound healingagents can be added, as well. Neomycin and bacitracin are examples ofcertain additives that are incorporated into a patch intended fortopical use, in addition to the antibacterial properties of EACAdiscussed above.

A hemostatic patch of the invention also is useful for treating animals,preferably humans or other mammals. Thus, both companion, livestock andwild animals can be treated with a hemostatic patch.

A patch in size and shape according to the intended use. Moreover, astandard size rectangular patch, 9.5×4.8 cm, having an uncompressedthickness of about 4-10 mm, or a compressed thickness of about 2-10 mm,advantageously 2-5 mm, may be cut to size with a pair of scissors.

One example of an advantageous matrix to which EACA and hemostaticagents and or other additives according to the invention are appliedincludes gelatin foam, preferably provided in a compressed form. Morepreferably, a GelFoam® matrix that is compressed to at least one-halfits original thickness.

Also, a patch may be spherically, conically, cuboidally orcylindrically-shaped or prefabricated into small squares, such as forpacking into a body cavity. Such an embodiment is useful for example,for a dental cavity resulting from tooth extraction. Additionally, thepatch can be configured into a tampon, for example, for epistaxis(profusely bleeding nostril) or other void.

A patch intended for topical applications additionally can be appliedwith an adhesive tape, as a band-aid form, where the patch is adhered toan adhesive backing. Preferably the adhesive used to secure the patch isporous in areas which contact the skin.

One or more additional layers of wound dressing material, preferably alayer which aids in absorption of blood or other exudants, can beapplied to a patch. Such an additional layer can be made as an integralpart of the patch, thereby creating a thicker patch. Alternatively, thelayer may be applied as a supplement to the backside (non-woundcontacting surface) of a patch according to the invention. Particularlyfor topical use, the layer(s) can contain superabsorbents to wickexudant solution from the wound site. It is advised that for patchesintended for internal-surgical applications, where an added layer(s) isintegral with the patch, the layer(s) should be both biodegradable andpharmaceutically acceptable.

The patch can be designed to facilitate its application to anastomose orfuse ends of a blood vessel or other body lumen having been severedsurgically or otherwise. To apply a patch for anastomosis, a rectangularGETR patch, for example, is wrapped around the external surface of theends of a Dacron® graft. When the graft is positioned into place, thepatch accelerates fibrin growth into the graft to seal the graft inplace (hemostatically and hermetically).

A kit is provided that contains a graft and a patch according to thepresent invention that is designed for fitting with the ends of thegraft. Alternatively, a kit is provided having a patch of the presentinvention pre-fitted onto at least one end of a graft.

Preferably, a wound-contacting surface of the patch is coated with acolor indicator to assist the user, such as yellow vitamin B₂(riboflavin) or a suitable dye, for example, hemin. By color coding thepatch, the user knowingly avoids touching or otherwise contaminating thewound-contacting surface of the patch.

A patch according to the invention is made by applying to a matrix, anamount of EACA effective for inhibiting fibrinolysis in the localenvironment of the matrix. Advantageously, about 10-100 mg/cm² of EACAis applied to a wound-contacting surface of the matrix, moreadvantageously 60-70 mg/cm².

EACA, as well as the other hemostatic agents or additives described ascomponents of a patch according to the invention, can be applied to thematrix by any of several methods which all would be performed mostadvantageously under sterile conditions. It is understood thatconventional methods of applying the hemostatic agents and additives toa matrix comprising EACA besides those described herein can be performedas well.

Advantageously, EACA is applied as a layer to a particular surface orside of the matrix, which surface is then designated as thewound-contacting surface.

This can be accomplished by spraying EACA in powder form onto the patch.Alternatively, a solution of EACA can be coated onto a matrix and driedby lyophilization or by conventional means. In another method ofapplying EACA, a matrix is dipped completely or partially into a sterilesolution of EACA such that a sufficient amount of EACA accumulateswithin the matrix effective to inhibit fibrinolysis in a mammal, suchthat similar effectiveness to the Hemarrest patch is demonstrated.

After application of EACA to a matrix, the matrix/EACA is coated with aprotein layer that facilitates EACA's adherence to the matrix.Advantageously, this protein is thrombin, although other proteinaceousor gelatin compound which facilitates such adherence could be utilized,as well. In a more advantageous embodiment, the matrix is coated with aprotein layer prior to application of EACA. In a further advantageousembodiment, the matrix is treated before and after addition of EACA witha protein, preferably which is in solution with an ion additive, such ascalcium (i.e., calcium chloride solution).

For example, embodiments such as GT(Ca++)E or CT(Ca++)E, are made byapplying to a wound contacting surface of a matrix of gelatin foam orcollagen, a first solution of thrombin dissolved in calcium chloride,the thrombin present at an amount, for example, between 1-1000 IU/cm²,advantageously 1-100 IU/cm², and more advantageously 1-4 IU/cm², or 1.25IU/cm². The thrombin is dissolved in 20-60 mM calcium chloride,preferably about 40 mM, such that an amount between 25-150micrograms/cm², preferably 50-100 micrograms/cm², is deposited onto thatsurface. The next step comprises applying to the thrombin-coated matrixsurface, 10-100 mg/cm² of epsilon aminocaproic acid, preferably 60-70mg/cm², and preferably in a powder form; then, applying a secondsolution of thrombin in calcium chloride, which, for example containsthe amounts of thrombin and calcium as described in the first solution;and then drying the thrombin, calcium chloride and epsilon aminocaproicacid on the patch. The amount of thrombin applied in the first andsecond solutions can vary, or, a single thrombin solution sealing stepcan be applied after addition of EACA. Preferably, the total amount ofthrombin applied to the wound-contacting surface of the patch by the twosteps is 2-10 IU/cm².

The drying step is accomplished by lyophilization, preferably. Otherdrying procedures appropriate for a material containing an activeprotein ingredient can also be employed, so long as the drying treatmentdoes not denature the proteins or render them inactive when exposed toanimal blood. Alternatively, the patch is conventionally dried, bymaintaining it at room temperature for a period of 1-3 hours, followedby refrigeration overnight.

In yet another embodiment, an agent added to a matrix, in addition toEACA, thrombin, calcium chloride, includes an amount of protaminesulfate effective to neutralize heparin in the local environment of thepatch. Protamine sulfate is added in an amount between 1-15 mg/cm² ofsaid matrix, preferably in an amount between 2-5 mg/cm² of a woundcontacting surface of the matrix.

Likewise, RGD or RGDS peptide can be dissolved in double distilled waterand sprayed onto a wound-contacting surface of the patch. A patchadvantageously contains an amount of RGD effective to enhance clotformation. RGD or RGDS is applied to a patch advantageously in an amountbetween 110-130 mg/cm². Thus, a standard size patch would contain about1-10 mg/patch or about 5-7 mg/patch of RGD or RGDS.

It should be noted that, like EACA, the hemostatic agents or additivesdescribed in the foregoing paragraphs can be applied to a matrix as alayer, for example, by spraying them onto the wound-contacting surfaceof the matrix in dried forms. Alternatively, a matrix can be dipped orcoated with a solution containing the hemostatic agent/additive. It isdesirable that the matrix and agents commingle, particularly when thepatch is exposed to a body fluid such as blood, which permits the driedagents to solubilize and mix. Thus, a patch can be provided wherein thehemostatic agent or mixture of hemostatic agents are absorbed into thepores or interstices of the matrix, or, the agents can be layered on asurface of the matrix and upon solubilizing the agents by addition ofbody fluid, the desired commingling is achieved.

The matrix can be coated with appropriate hemostatic agents described inthe above embodiments on one or all surfaces. In a preferred embodiment,the hemostatic agents and additives are coated on only one surface (thewound-contacting surface). Such an arrangement avoids inducinghemostasis between the wound and a non-wounded tissue in the vicinity ofthe patch. In an embodiment intended for packing a void in body tissue,for example, the patch is coated with hemostatic agent(s)/additive(s) onall surfaces.

A kit according to the invention comprises any of the above describedhemostatic patch embodiments (which vary in ways including hemostaticagent(s) and additive(s) utilized, shape or size) according to theinvention and a package, wherein the patch is contained within a sealedsterile package which facilitates removal of the patch withoutcontamination. The kit can contain multiple patches, preferably whereineach patch is contained within a separate sealed sterile package. A kitdesigned for field/military use can, in addition to a hemostatic patch,further include disposable pre-sterilized surgical instruments, such asa scalpel, clamp, tourniquet, elastic or inelastic bandage, or the like.

Another type of kit comprises a patch containing agents added to thematrix including thrombin, EACA calcium chloride, and protamine sulfate.Such a kit can be prescribed, for example, to patients requiringanticoagulant therapy, to avert the risk of serious bleeding which canoccur from a minor injury. The availability of such a patch can reducepostoperative hospitalization for patients on dicumarol who underwentsurgery.

The present invention is further described with reference to thefollowing, illustrative examples. Unless defined otherwise, alltechnical and scientific terms used herein have the same meaning ascommonly understood by one of ordinary skill in the art of theinvention. Although any methods and materials similar or equivalent tothose described herein can be used in the practice of the invention, thepreferred methods and materials have been described. Unless mentionedotherwise, the techniques employed or contemplated herein are standardmethodologies well known to one of ordinary skill in the art. Thematerials, methods and examples are illustrative only and not limiting.

EXAMPLE 1 THE EFFECTS OF EACA ON THROMBIN ACTIVATION

A two-part experiment was designed to test whether thrombin activationin the presence of EACA (A) is accelerated and (B) is pH dependent.

A. Effect of Time Incubated at 37° C.

The first part of this study examined activation of thrombin and itsdegradation in H₂ O after incubation at 37° C. The assay used was acolorimetric cleaving of a tripeptide, TFA-phe-pro-arg-AFC, where theAFC is the colorometric tag. Seventeen mg of this substrate wasdissolved in 200 μl DMSO. Thrombin was made up as 10 units/mi. The"TEST" solution contained 100 μl substrate and 200 μl of the thrombinsolution; a blank contained the same amount c. substrate and 200 μl ofH₂ O.

FIG. 1 labeled as "ACTIVATION OF THROMBIN SOLUTION AT 37° C." shows theresults of that experiment. The optical density in all of theseexperiments is an indication of the color and therefore the amount ofcleavage of the enzyme that has taken place.

The slope of the black-box line indicates that thrombin activation ofthrombin dissolved in H₂ O takes place slowly over a 172 minute timeperiod. The blank, containing substrate and H₂ O, shows no change inoptical density, indicating that no activation, or cleaving of thepeptide has occurred.

B. Thrombin Activation by EACA: A pH Effect

In this experiment, the hypothesis that the activation of thrombin byEACA was due to EACA's effect of increasing pH was tested.

All solutions were prepared at the same concentration as indicated inpart A above, except EACA which was made up at a concentration of 50mg/ml. The following samples were prepared:

1. 50 μl Thrombin+925 μl H₂ O+25 μl substrate

2. 50 μl Thrombin+925 μl Tris buffer@ pH 7.02+25 μl substrate

3. 50 μl Thrombin+925 μl Tris buffer@ pH 7.62+25 μl substrate

4. 50 μl Thrombin+925 μl Tris buffer@ pH 7.80+25 μl substrate

5. 50 μl Thrombin+925 μl Tris buffer@ pH 8.01+25 μl substrate

6. 50 μl Thrombin+425 μl EACA sol.+500 μl H₂ O+25 μl substrate

7. 50 μl Thrombin+425 μl EACA sol.+500 μl Tris buffer@ pH 7.02+25 μlsubstrate

8. 50 μl Thrombin+425 μl EACA sol.+500 μl Tris buffer@ pH 7.62+25 μlsubstrate

9. 50 μl Thrombin+425 μl EACA sol.+500 μl Tris buffer@ Ph 7.80+25 μlsubstrate

10. 50 μl Thrombin+425 μl EACA sol.+500 μl Tris buffer@ Ph 8.01+25 μlsubstrate

Each tube was placed in a 37° C. waterbath and removed periodically tobe read each 5' for a total of 60'. Results are summarized in FIG. 2. Inthe legend, samples 1-10 listed vertically in the legend correspond tosamples 1-10 immediately above, while "T" represents thrombin.

The results indicate clearly that the action of EACA is a pH effect andthat Tris buffer-adjusted solutions had a similar effect as the pH wasincreased. In all cases, the plateau may not be accurate since thesaturation of the instrument occurs near to the maximum optical densityrecorded.

At 37° C., the results indicated clearly that the action of EACA is a pHeffect. Calcium ion appears to enhance this pH-mediated activation.

EXAMPLE 2 EACA EXERTS AN ANTIBACTERIAL EFFECT

EACA was shown to inhibit both Staph. aureus and E. coli in adose-dependent manner by the following method.

Culture plates and EACA discs were prepared as follows: Whatman filterpaper discs of 5.4 cm in diameter and 22.9 cm² in area were placed inbeakers of almost the same diameter. EACA (229 mg) was dissolved in 250μl of double distilled H₂ O and used to make the final concentrations.All concentrations of EACA were applied in 250 μl of H₂ O.Concentrations of 0, 10, 20, 30, 40, 50, 60, 70, 80, 90 and 100 mg/cm²were prepared. After application of EACA solutions, the discs wereallowed to dry and frozen to ensure stability.

Discs for application to agar plates were made with a paper punch, at asize of about 6.35 mm. Agar plates were poured in two increments.

A first increment of 1.5% Brain-Heart Infusion agar was prepared andautoclaved. After cooling to approximately 55° C., 12 mls were added toeach 100 mm×15 mm petri dish. Plates were allowed to cool to roomtemperature, wrapped in parafilm and refrigerated. Brain-Heart Infusionbroth was prepared and autoclaved. When the temperature was cooled toroom temperature, a 1 ml aliquot of Staph. aureus or E. coli was addedand the broth incubated overnight at 37° C.

The following day, a second increment of 1.2% Brain-Heart Infusion agarwas prepared and when cooled to 48° C. after autoclaving, 2 ml of eachculture was added to separate flasks of agar and 1 ml of these mixtureswas added to each culture plate. This top layer was allowed to harden atroom temperature. Two sets of five discs containing EACA at varyingconcentrations were added to each plate, in addition to a control disccontaining zero mg/cm² EACA. The complete results are listed in Table 2.FIG. 3A and FIG. 3B each show inhibition by EACA of Staph. aureus growthgraphically, for each set of various concentrations of EACA, while FIGS.4A and FIG. 4B each show inhibition by EACA of E. coli growth for eachset of varying concentrations of EACA.

Results of observation and measurement of the zone inhibition revealthat in almost all instances, there is an incremental change in thiszone of inhibition related to the concentration of EACA. The exceptionsare that the 60 mg/cm² did not follow the trend, but was equal to ordecreased in relation to the 40 mg/cm². The 90 and 100 mg/cm² zones werenot always increases. The consistency of these variations appear to berelated to the disc preparation rather than a biological variation.

                                      TABLE 2                                     __________________________________________________________________________    Results: Inhibition of E. coli (Plates 1-6) and                               Staph. aureus (Plates 7-12) Growth by EACA                                                  Conc. of                                                                           DIAMETER                                                        Plate    EACA in                                                                            OF     % >   % OF                                          Date Number                                                                            Organism                                                                           mg/cm2                                                                             INHIBITION                                                                           CONTROL                                                                             MAXIMUM                                       __________________________________________________________________________    10/22/93                                                                           1   E. coli                                                                            control                                                                            6.35   0.00  77.00                                                       10   6.95   9.40  84.20                                                       30   7.65   20.50 92.70                                                       50   7.75   22.00 93.90                                                       70   8.25   29.90 100.00                                                      90   7.50   18.10 90.90                                         10/22/93                                                                           2   E. coli                                                                            control                                                                            6.35   0.00  70.20                                                       10   6.70   5.50  74.00                                                       30   8.55   34.60 94.50                                                       50   8.60   35.40 95.00                                                       70   9.05   42.50 100.00                                                      90   8.35   31.50 92.30                                         10/22/93                                                                           3   E. coli                                                                            control                                                                            6.35   0.00  70.60                                                       10   6.70   5.50  74.40                                                       30   7.05   11.00 78.30                                                       50   7.10   11.80 78.80                                                       70   9.00   41.70 100.00                                                      90   8.25   29.90 91.70                                         10/22/93                                                                           4   E. coli                                                                            control                                                                            6.35   0.00  77.40                                                       20   7.05   11.00 86.00                                                       40   7.70   21.30 93.90                                                       60   7.70   21.30 93.90                                                       80   8.20   29.10 100.00                                                      100  7.75   22.00 94.50                                         10/22/93                                                                           5   E. coli                                                                            control                                                                            6.35   0.00  78.40                                                       20   7.70   21.30 95.10                                                       40   7.75   22.00 95.70                                                       60   7.45   17.30 92.00                                                       80   8.10   27.60 100.00                                                      100  8.10   27.60 100.00                                        10/22/93                                                                           6   E. coli                                                                            control                                                                            6.35   0.00  76.50                                                       20   7.60   19.70 91.60                                                       40   8.10   27.60 97.60                                                       60   7.90   24.40 95.20                                                       80   8.25   29.90 99.40                                                       100  8.30   30.70 100.00                                        10/22/93                                                                           7   S. aureus                                                                          control                                                                            6.60   0.00  77.20                                                       10   7.55   14.40 88.30                                                       30   8.20   24.20 95.90                                                       50   7.65   15.90 89.50                                                       70   8.55   29.50 100.00                                                      90   7.90   19.70 92.40                                         10/22/93                                                                           8   S. aureus                                                                          control                                                                            6.55   0.00  80.90                                                       10   7.10   8.40  87.70                                                       30   7.00   6.90  86.40                                                       50   7.15   9.20  88.30                                                       70   7.75   18.30 95.70                                                       90   8.10   23.70 100.00                                        10/22/93                                                                           9   S. aureus                                                                          control                                                                            6.55   0.00  81.90                                                       10   7.00   6.90  87.50                                                       30   7.20   9.90  90.00                                                       50   7.45   13.70 93.10                                                       70   7.85   19.80 98.10                                                       90   8.00   22.10 100.00                                        10/22/93                                                                           10  S. aureus                                                                          control                                                                            6.60   0.00  79.00                                                       20   8.05   21.90 96.40                                                       40   8.30   25.80 99.40                                                       60   8.10   22.70 97.00                                                       80   7.55   14.40 90.40                                                       100  8.35   26.50 100.00                                        10/22/93                                                                           11  S. aureus                                                                          control                                                                            6.50   0.00  83.90                                                       20   7.20   10.80 92.90                                                       40   7.70   18.50 99.40                                                       60   7.30   12.30 94.20                                                       80   7.40   13.80 95.50                                                       100  7.75   19.20 100.00                                        10/22/93                                                                           12  S. aureus                                                                          control                                                                            6.50   0.00  79.30                                                       20   6.75   3.80  82.30                                                       40   8.05   23.80 98.20                                                       60   8.00   23.10 97.60                                                       80   8.20   26.20 100.00                                                      100  7.20   10.80 87.80                                         __________________________________________________________________________

EXAMPLE 3 A COMPARISON BETWEEN G(Ca++)TE AND TACHOCOMB®

A. Experimental Conditions

1. Patch Preparation

An absorbable gelatin sponge, namely a gelatin foam matrix (GelFoam®,Upjohn Co.) was obtained. Physician's Desk Reference 2451, 47th EditionDowd (ed.), Medical Economics Data (1993). Thereafter, 1.25 IU/cm²bovine thrombin was applied to a surface of the gelatin foam. Next,either 10 mg/cm² or 100 mg/cm² of EACA was applied to that same surface,followed by an application of another 1.25 IU/cm² application of bovinethrombin. The patches were allowed to dry and left in a refrigeratorovernight. A "blank" gelatin foam patch, which was not treated withthrombin or EACA was also tested in the kidney.

TachoComb® patches were obtained and applied according to themanufacturer's instructions. That is, prior to preparation, theTachoComb® patches were dipped in sterile saline and applied to bleedingorgans with light pressure for five minutes.

2. Organ Preparation

A lobe of pig liver was surgically isolated and three lesionsapproximately 1×1.5 cm in size were created. Blood flowed freely fromeach of the lesions. Each of the patches discussed in part A. (above),were applied and kept under pressure by a saline soaked sponge for fiveminutes and the pressure was released. Patches were evaluated by theirability to control hemorrhage in terms of (a) leakage, (b) ability towithstand increased vascular pressure, (c) the resistance offered whenattempting to peel the patch from the lesion, and (d) events of clotformation in the lesion.

For the liver, pressure tests were performed by raising the arterialpressure by injecting 0.2 ml 1/1000 epinephrine.

For renal studies, both poles (ends) of the kidney were surgicallyremoved to a depth of approximately 0.5 cm, while the renal artery wasclamped. The clamp was removed after the test patches were placed andpressure applied with a saline soaked surgical sponge for five minutes.

B. Summary of Results

In liver, when the pressure was removed and after five minutes, bothpatches according to the invention showed good control of hemorrhage,with only a little bleeding from the edge in the 100 mg patch and nobleeding from the 10 mg patch. After 9-13 minutes, the TachoComb® patchwas the only patch leaking or bleeding from the edge.

A small amount of blood was present on the surface of the 100 mg patch,while none was present on the 10 mg patch.

When the patches were removed from the same liver free blood was presentcoming from the 100 mg and TachoComb® lesions. A greater flow wasobserved coming from the TachoComb® patch. Much of the clot from theTachoComb® site stayed with the patch when it was peeled back. A pieceof the gelatin foam patch was incorporated into the 10 mg site.

When epinephrine was injected, the TachoComb® patch still dripped bloodfrom the edges after 18 minutes. The peel test after 20 minutes showedthe TachoComb® patch with minimal adhesion, the clot stuck to the patch,and the wound continued to bleed. In the lesion with the 100 mg patch,blood also flowed, but not as much as the TachoComb® patch. The 10 mgpatch had the least bleeding of any of the patches and had both goodincorporation of the patch into the lesion and good clot formation, withsome minimal adhesion to the periphery.

In the kidney, there was not much difference between the TachoComb® andthe 100 mg patch lesions. There was no bleeding before or afterepinephrine injections. When the patches were peeled at 20 minutes, theTachoComb®patch had very good adhesive qualities, good clot formation,but some free blood. The 100 mg patch did not have as good adhesiveness,but had a well-formed clot and no hemorrhage. When a blank gelatin patchand 10 mg patches according to the invention were compared, the 10 mgpatch definitely was better. Five minutes after the pressure release,there was free blood under the 100 mg patch while there was somebleeding around the edge of the 10 mg patch. This was unchanged afterepinephrine, but when an experimental peel test was done by removing thepatch and observing clot formation, the clot was not as well-formedunder the blank patch. Further, free blood was present, and there was ablot stain dark with blood on the dry surgical sponge held against thepatch to detect blood or serum penetrating the patch. There was goodadhesion of the 100 mg patch to the surface even when the patch isremoved. The 10 mg patch had fair adhesion around the edges and somefree blood. When the patch was lifted there was evidence of good clotformation and no bleeding, thereby providing a light pink blot testmeasured by the dry surgical sponge held against the patch.

When a patch containing 2.5 IU/cm² thrombin and 100 mg/cm² epsilonaminocaproic acid was applied to a kidney lesion. A light pink color wasseen which indicated that virtually no free blood penetrated through thepatch. No blood was present on the sponge that held the hemostatic patchagainst the organ.

A lesion on the opposite pole of the same kidney was covered with aTachoComb® patch. The latter patch was darker, which indicates that moreblood was coming through the patch matrix. The lower edges of that patchwere looser as compared to the hemarrest patch. Fresh blood could beseen on a dry sponge held against the organ for the purpose of aiding indetection of fresh blood.

EXAMPLE 4 HEMOSTATIC EFFICACY ACHIEVED BY THE GE(Ca++) PATCH

1) Pig splenic lesions were created as discussed in Example 3. As seenin FIG. 10, no leakage was observed from the GE(Ca++) patch, while somewas observed from the GT(Ca++)E patch. In 10 minutes, there was slightleakage from the centers of both, which was stopped by 15 minutes. Whenthe patches were removed, there was no difference in a test blottingperformed on the surface of the patch, as both test blots were lightpink. Very good adhesion was observed for both patches, as well aslarge, well-formed clots. In the GE(Ca++) patch, the clot adhered to thepatch but not the lesion.

2) In the liver, neither showed bleeding at any observation. Whenpeeled, the patches both had good adhesion, but the GE(Ca++) patch bledfreely after the patch was removed. In contrast, the GT(Ca++)E patch hadsome incorporation and a good clot. The GE(Ca++) did not seem to have agood clot.

3) The kidneys had unexpected findings. The GE(Ca++) patch had noevident leakage while the GT(Ca++)E leaked steadily. At 10 minutes, theleakage had lessened in the GT(Ca++)E patch, and at 15 minutes, therewas no further leakage in either. When the patches were removed, bothhad good adhesion, some incorporation of the GT(Ca++)E patch, but bothbled in the absence of the patch.

The conclusion from this one experiment suggests that there is littledifference between the treatments although clot formation appears to bebetter with the addition of thrombin. This means that a first-aidbandage that is stable under more severe exposure to heat may beeffective without the presence of thrombin.

EXAMPLE 7 THE ("RGD") PATCH

The study has both parts I and II.

Part 1: Patches CTR, CTE(f), GT(f)E(f) and a plain gelfoam (G) patchwere applied to lesions made on the spleen of an anesthetized pig. Thesymbol "(f)" denotes the compound immediately preceding it as afreshly-applied compound. That is, E(f) denotes EACA that is freshlyapplied to a patch very soon (less than about three hours) after it ismade.

1) Leakage: When the sponge pressure was removed from the patches, the Gpatch had virtually no leakage. This was true of the CTE(f)R patch aswell, but the CTR patch showed much bleeding. Shortly thereafter, theresults were recorded as similar.

2) Peel/Adhesion: All three patches stuck to the saline-soaked spongesand removal of sponge pressure was done carefully to prevent theirremoval from the lesion; thus adhesion in all patches was minimal atthat time. Patch G did show some adhesion, but CTR and CTE(f)R showedgood adhesion even though they each had some clot formation, best inCTE(f)R. Approximately 6 minutes after removing the pressure, thegelatin foam showed very good adhesiveness and poor clot formation.Neither of the other patches showed good adhesion qualities, while theCTR some clot and CTE(f)R had a large, excellent clot.

Part II: More lesions were created on the spleen and all results werecompared. Patches applied were CTE(f) and GT(f) E(f).

1) Leakage: Neither the CTE nor the GT(f)E(f) patch showed leakage atremoval of sponge pressure. Five minutes later, the vein was occludedand intravascular pressure increased and lesions made in both parts wereevaluated. The time for the increased pressure test performed after thesponge was released in Part I is 27 minutes and in Part II, only 5minutes. The gelatin foam only patch (G) was not leaking at all; neitherwere CTR, ** CTE(f)R. In comparing the two patches with T and EACA usingeither the gelatin foam or collagen matrix, the gelatin foam patch,GT(f)E(f), showed less leakage than the collagen based patch, CTE. Infact, the CTE patch leaked more as the venous pressure was raised.

2) Peel/Adhesion: Two minutes after removing the sponge pressure andwhen comparing CTE(f), collagen+T+EACA and GT(f)E(f), the gelatin foambased patch similarly treated showed very good adhesion to both thelesion and the surrounding tissue. The CTE patch with the collagen basehad little or no adhesion. 10 minutes after removing sponge pressure(part II patches GT(f)E(f) and CTE(f)) and with the intravascularpressure still elevated, all patches from Part I and Part II wereevaluated together. The time interval was about 32 minutes after initialsponge pressure removal for those patches from Part I (CTR, G, andCTE(f)R). The results were as follows: Patch CTR) No adhesion, good clotformation and little leakage. Patch G) Strong adhesion to surroundingtissue, no adhesion to lesion, much leaking. Patch CTE(f)R) No adhesion,good clot formation, little leakage. Patch GT(f)E(f)) Good adhesion tolesion, good clot formation, little leakage. Patch CTE(f) No adhesion,good clot formation, little leakage.

3) A further assessment of splenic lesions was made (Part I) 58 minutesafter initial sponge pressure release, Part II, -36 minutes afterinitial pressure release. The patches were removed at this time. Theresults of this assessment are: Patch TR) Moderate clot formation,little, if any, leakage. Patch G) Leakage, but remainder of gelatin foamstuck to lesion. Patch CTE(f)R) Excellent clot, no leakage. PatchGT(f)E(f)) Good clot formation, little, if any, leakage. Patch CTE(f)good clot formation, virtually dry.

4) A final assessment of these splenic lesions was made 37 minuteslater. Patch CTR) Dry to the blot test (placing a dry surgical sponge onthe lesion), clot is developed, no collagen incorporated into lesion.Patch G) Dry to the blot test, gelatin foam incorporated into thelesion. Patch CTE(f)R) Absolutely no blood elements on sponge afterblotting; clot is excellent, filling lesion and extending onto thesurrounding normal area. Patch GT(f)E(f)) Serum staining on sponge, butgood clot and gelatin sponge incorporated into the lesion. Patch CTE(f)Dry to blot test; similar to CTE(f)R.

We claim:
 1. A dry sterile storage stable fibrinogen-free hemostaticpatch comprising a biodegradable matrix selected from the groupconsisting of absorbable gelatin, calcium alginate, calcium/sodiumelginate, collagen and oxidized regenerated cellulose, and containing ahemostasie-promoting amount of thrombin and an amount of epsilonaminocaproic acid effective to raise the pH of the local environment ofa bleeding wound surface onto which the hemostatic patch is applied to avalue in the range of 7.0-9.0, inclusive, effective to accelerate theactivation of the thrombin of the hemoetatic patch and thus accelerateclot formation at the interface between the wound surface and thehemostatic patch.
 2. A hemostatic patch according to claim 1, whereinthe amount of the epsilon aminocaproic acid is effective to raise the pHto the range of 7.62-8.02, inclusive.
 3. A hemostatic patch according toclaim 1, wherein the biodegradable matrix is a foam.
 4. A hemostaticpatch according to claim 1, wherein the biodegradable matrix isabsorbable gelatin.
 5. A hemostatic patch according to claim 1, whereinthe patch contains one or more of a source of calcium ions, RGD peptide,RGDS peptide, protamine sulfate and buffer.
 6. A hemostatic patchaccording to claim 1, in the form of a flexible sheet.
 7. A hemostaticpatch according to claim 1, wherein the thrombin is bovine thrombin. 8.A hemostatic patch according to claim 1, wherein the epsilonaminocaproic acid is present in an amount from about 10-100 mg/cm² ofthe wound-contacting surface of the matrix.
 9. A hemostatic patchaccording to claim 1, wherein the thrombin is present in an amountbetween 1-4 IU/cm² of the wound-contacting surface of the matrix.
 10. Ahemostatic patch according to claim 1, wherein calcium ions are presentin the hemostatic patch in an amount equivalent to between 25-150micrograms CaCl₂ /cm² of the wound-contacting surface of the matrix. 11.A hemostatic patch according to claim 1, wherein the biodegradablematrix is a flexible sheet of an absorbable gelatin foam; wherein thepatch optionally contains one or more of a source of RGD peptide, RGDSpeptide, protamine sulfate and buffer; wherein epsilon aminocaproic acidis present therein in an amount between 60-70 mg/cm² of thewound-contacting surface of the matrix; wherein the thrombin is presenttherein in an amount between 1-4 IU/cm² of the wound-contacting surfaceof the matrix; and wherein calcium ions are present in an amountequivalent to between 25-150 micrograms of CaCl₂ /cm² of thewound-contacting surface of the matrix.
 12. A sterile package containinga hemostatic patch according to claim
 1. 13. A sterile packagecontaining a hemostatic patch according to claim
 11. 14. A method forstanching bleeding from a wound, which comprises applying to the woundedsurface a hemostatic patch according to claim
 1. 15. A method forstanching bleeding from a wound, which comprises applying to the woundedsurface a hemostatic patch according to claim
 11. 16. A method accordingto claim 14, which comprises manually pressing the hemostaticagent-containing surface of the patch against the wounded surface for aperiod of time until clotting has occurred at the interface between thehemostatic patch and the wounded surface.
 17. A method according toclaim 15, which comprises manually pressing the hemostaticagent-containing surface of the patch against the wounded surface for aperiod of time until cloting has occurred at the interface between thehemostatic patch and the wounded surface.